Fluidic switching apparatus

ABSTRACT

AN INFORMATION DISPLAY OF THE TYPE IN WHICH ALPHANUMERIC CHARACTERS MOVE CONTINUOUSLY ACROSS A VIEWING FIELD. EACH CHARACTER IS FORMED BY THE &#34;SWITCHING&#34; OF AN APPROPRIATE GROUP OF ELEMENTS IN A RECTANGULAR CHARACTER MATRIX. THE ELEMENTS ARE ROTATABLE DISCS, WHICH ARE SWITCHED BY FLIPPING THEM OVER. THE ELEMENT SELECTION LOGIC, AND THE SWITCHING ENERGY AS WELL, IS ACHIEVED THROUGH FLUIDIC MEANS. EACH DISC ELEMENT IS CONFRONTED WITH A POWER JET, AND A CONTROL JET CAPABLE OF CHANGING THE CHARACTER OF THE POWER JET FROM LAMINAR TO TURBULENT. THE DISCS EXPERIENCE A SWITCHING TORQUE WHEN IMPULSED BY A LAMINAR POWER JET, BUT THE TURBULENT CONDITION OF THE POWER JET DISTRIBUTES ITS IMPACT IN SUCH A MANNER THAT THERE IS NO LONGER SUFFICIENT NET TORQUE TO FLIP THE DISC. THUS, BY PROPER SELECTION OF THE CONTROL JETS, AN APPROPRIATE PATTERN OF ELEMENTS CAN BE SWITCHED ON.

Oct. 12, 1971 R. F. OKEEFE 3,611,598

FLUIDIG SWITCHING APPARATUS Filed 001;. 13, 1969 2 Sheets-Sheet 1 FIG I I08 I NO I l bzL: W

l I02 J H2 FIG. 2 no INVlz'N'l'OR. ROBERT F. O'KEEFE ATTORNEY Oct. 12, 1911 R. F. O'KEEFE 3,611,598

FLUIDIC SWITCHING APPARATUS Filed Oct. 13, 1969 2 Sheets-Sheet 2 FIG. 5

5l0 Slb IN VENTOR. ROBERT p, O'KEEFE ATTORNEY United States Patent 3,611,598 FLlUliDIC SWIITCHKNG APPARATUS Robert IF. OKeete, Trumbull, Conn, assignor to Pitney-Bowes, 1nc., Stamford, Conn. Eiied Oct. 13, 1969, Ser. No. 865,941 lint. Cl. G091 11/00 U.S. Cl. 40-48 C 22 Claims ABSTRACT OF THE DISCLOSURE An information display of the type in which alphanumeric characters move continuously across a viewing field. Each character is formed by the switching of an appropriate group of elements in a rectangular character matrix. The elements are rotatable discs, which are switched by flipping them over. The element selection logic, and the switching energy as well, is achieved through fluidic means. Each disc element is confronted with a power jet, and a control jet capable of changing the character of the power jet from laminar to turbulent. The discs experience a switching torque when impulsed by a laminar power jet, but the turbulent condition of the power jet distributes its impact in such a manner that there is no longer sufl'icient net torque to flip the disc. Thus, by proper selection of the control jets, an appropriate pattern of elements can be switched on.

Field of the invention This invention relates generally to fluidic switching apparatus, and it is particularly applicable to a fluidic character display for transportion terminals, television prompting, sporting events, stock transactions and the like.

The prior art In U.S. Pat. No. 3,374,565 of R. L. Woolfolk there is seen a moving alphanumeric character display in which a readable message is generated at a writing station, then moves across a viewing field, and is finally erased. This type of display is particularly appropriate for stock price quotation boards, news displays, or other applications where information is continuously being updated. Each character is created from a matrix of switchable disc elements. There is a writing station at which the appropriate character-forming combination of elements in each matrix is switched on by flipping the discs 180 degrees. The opposite sides of the discs have contrasting colors, so that those discs which have been flipped stand out visually in contrast to those which have not been flipped. A number of character matrices of this type are mounted on an endless conveyor belt which carries each matrix in turn past the writing station, through a viewing field, past an erasing station, and then back to the writing station.

Woolfolks writing mechanism, however, leaves something to be desired. The energy for flipping the discs is provided by a fluid power jet, specifically a brief pulse of air which is aimed to strike the disc on one side of its axis of rotation only. Such a pulse is effective to flip its associated disc to the opposite side. Selecting the appropriate combination of discs depends upon a plurality of valves, one for each power jet, and appropriate logic controls for opening groups of these valves in the required characterforming pattern. Such a mechanism for controlling high power jets, requires moving parts and is subject to the reliability limitations of moving part devices.

THE INVENTION This invention avoids the disadvantages of valved logic for controlling the power jet directly, by employing a laminar-to-turbulent fluidic switching device of the type disclosed in US. Pat. No. 3,469,593. Any rotatable element, such as the character-forming disc described above, is mounted for angular movement between two stable positions. A power conduit is arranged to direct a fluid power jet at the element at selected time intervals, and is aimed so that the element is flipped from one operating position to the other by the net torque exerted thereon when the jet is laminar, but not when it is turbulent. Control means are also provided for making the jet turbulent during selected intervals, so as to prevent the element from responding at such times.

In a preferred form of the invention, the power jet is aimed so that it strikes entirely on one side of the axis of rotation of the element when laminar, but when it is turbulent its impact is distributed over both sides of the axis, reducing or eliminating the net switching torque.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of one embodiment of a fluidic switching device in accordance with this invention. In this view the control jet is off, and the power jet is laminar.

FIG. 2 is a similar view of the same device, but with the control jet on, rendering the power jet turbulent.

FIG. 3 is a similar view of an alternative embodiment of a switching device in accordance with this invention.

FIG. 4 is a similar View of another alternative embodiment of switching device in accordance with this invention, for use with a stationary alphanumeric character display.

And FIG. 5 is a side elevational view, with parts broken away for clarity of illustration, of an entire writing station employing switching apparatus in accordance with this invention, and designed for use in a moving alphanumeric character display.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is seen a switchable element in the form of a planar disc, vertically oriented and viewed edgewise in the drawings. The disc is mounted for rotation about a horizontal axis by means of pivots 102, only one of which is visible in the drawing. The disc is able to assume two gravity-biased or other stable positions, both of which are defined by a fixed stop member 104. In the solid line representation of the disc element 100, it is held gravitationally in a substantially vertical position, and contacts the rear surface of the stop member 104. The other stable position is achieved by rotating disc element 100 nearly 180 degrees about pivots 102 in the direction indi cated by arrow 106, so that it passes through the dashed line position seen in FIG. 1, and the portion of the disc element 100 which was originally uppermost swings downwardly to strike against the front surface of the stop member 1041. Any suitable means may be used to yieldably retain said disc in said positions.

For use as a character element .in an alphanumeric display, the opposite sides of the disc element 100 have contrasting colors, so that the described switch of disc positions produces a visible color change. By providing a rectangular matrix of disc elements 100, and switching these discs in the proper spatial configuration, any desired alphanumeric character can be formed in one color, and read against the background of the contrasting color.

It is conventional to switch such disc elements with air jets, for example, the laminar power jet 108 seen issuing in from conduit 110 in FIG. 1. The conduit is aimed high enough so that the laminar jet strikes entirely above the horizontal axis of rotation defined. by the pivots 102. The laminar jet 108 has little tendency to spread, over the short distance between the delivery end of conduit 110 and the confronting surface of the disc 100. Thus it exerts a 3 suflicient torque in the angular direction of arrow 106 for flipping the disc 100.

When the disc 100 is to remain in its original position instead of being flipped, the prior art can accomplish this only by shutting off the power jet 108 entirely, by means of a large valve able to control high fluid power levels. In the context of an alphanumeric character display involving a plurality of disc elements, many power conduits 110 and their associated valves are required, along with appropriate control logic for opening and closing these valves in the appropriate pattern.

In contrast, the present invention employs a low power control jet 114 delivered by a conduit 112 for switching control purpose. The conduit 112 terminates in a right angle bend which directs the jet 114 laterally against power jet 108. The control jet is off when the disc 100 is to be switched, and on when switching is to be inhibited. At times when the control jet 114 is on, its impact causes the power jet 108 to become turbulent, and thus to spread out as depicted on FIG. 2. The spacing between the tip of the power conduit 110 and the confronting surface of the disc element 100, as previously noted, is small enough to preclude excessive Spreading of the power jet 108 when it is laminar; but it is large enough so that when the jet is turbulent it will spread to such an extent that it no longer delivers sufficient torque to flip the disc element. A portion of the turbulent jet 108 strikes the upper portion of the disc element 100 (i.e. above the pivots 102); but a portion of it also misses the disc entirely, or preferably strikes the disc below the pivots 102, thus imparting an opposite torque impulse thereto, which counteracts the torque in the direction of arrow 106. As a result, insufficient net torque is imparted to the disc element 100 to switch it. Thus, by providing suitable valves or no-moving part fluidic switches for controlling the low power control jet 114, the high power jets 108 can be rendered efi'ective or ineifective selectively in any desired character-forming pattern.

In another version of the fluidic switching apparatus of this invention, FIG. 3 shows the same rotatable disc element 100 mounted upon pivots 102 and having two gravity-biased stable positions defined by stop element 104. In this device a power conduit 310 terminates in an enlarged chamber 316 similar to the interaction chamber described in said U.S. Pat. 3,469,593. A power jet 308 issuing from the power conduit 310 does not expand to fill the chamber 316 when it is in its laminar condition; but when it is driven turbulent by a control jet 314 issuing from a control conduit 312, the power jet 308 flares exponentially due to influence of the surrounding walls and thus expands more rapidly than the turbulent jet 108 in FIG. 2. This permits the equipment designer to employ a closer spacing between the outlet of the passageway 310, 316 and the switchable disc element 100, yet still obtain the degree of spreading of the turbulent power jet 308 which is necessary to inhibit switching of the disc element. Such closer spacing has several advantages. It reduces fluid power consumption to a minimum; since the power jet 308 has less room to spread when the distance which the jet must traverse to flip the disc 100 is smaller, and therefore the volume of air required to deliver a given impulse is less. It also reduces the horizontal depth of the switching mechanism, which saves space and materials. Finally, there is some tendency for the laminar power jet to be driven turbulent by ambient sonic noise, and the vulnerability of the device in this respect is decreased when the distance over which the jet is exposed to noise is diminished.

The nature of the control logic for switching the appropriate character-forming group of disc elements depends upon the type of display application. FIG. 4 illustrates an arrangement which is adapted for writing characters in a stationary alphanumeric display. Each disc element 100 in each character matrix over the viewing field of the display is provided with its own setting logic comprising the power conduit 100 and control conduit 4 112, just as described in connection with FIG. 1. In addition, however, each such disc element is also provided with a power conduit 400 and a control conduit 412 for the purposes of performing and controlling the disc resetting operation.

When it is time to write a message on a stationary display of this type, by switching certain discs and not others in the appropriate geometrical pattern, power jet pulses are issued simultaneously from all of the setting power conduits of the entire stationary display. If all these jets were laminar, of course, each element 100 in the entire display would switch, as indicated by arrow 106, and there would be no message. However, control jet pulses are also issued at the same time from selected ones of the control conduits 112, so that the associated power jets are made turbulent and are consequently ineffective in switching the associated discs 100. By a proper selection of the spatial pattern of the discs which are switched and those which are inhibited, the desired alphanumeric characters are generated. To reset any of the discs 100 for the purposes of erasure, all the reset power conduits 400 in the entire character display must be pulsed to issue reset power jets. When laminar, these jets impact against the disc elements 100 below the horizontal axis of rotation defined by the pivots 102, and therefore are effective to flip a previously switched disc back to its original position, as indicated by arrow 406. In order that the reset power conduits 400 may thus be pulsed indiscriminately without erasing the entire message, the reset control conduits 412 inhibit selected reset power jets according to the desired spatial pattern.

For a moving conveyor type of alphanumeric display, there is provided the type of writing head shown in FIG. 5, comprising a single vertical column of writing devices located at a writing station in advance of the display field window. For example, if each character matrix is an array of disc elements 100, five elements in width by seven elements in height, successive vertical columns of seven elements are continuously transported horizontally past the writing station, and the writing apparatus has a single vertical column of seven individual disc flipping devices of the kind described above. All seven devices might be incorporated in a single block 520, for example molded of a plastic material, into which appropriate fluid passages are cut. Each of these individual disc flipping devices includes a channel formed in the side of block 520 for defining a power jet conduit 510 which terminates in an expansion chamber 516, and another channel also formed in the side of the block 520 for defining a control conduit 512 which hooks laterally into the chamber 516. All seven writing devices are completed by adding a second plastic block 522, broken away for clarity of illustration, which is secured to the side of the block 520 adjacent the channels 510, 512, and 516, to provide a side wall therefor.

It will be appreciated from the preceding discussion that, whenever the control logic does not permit a control jet pulse to pass through a particular control conduit 512 at the time that a power jet pulse emerges from the associated power jet conduit 510, the associated power jet pulse passes through the expansion chamber '516 in a laminar and essentially unexpanded condition, and impacts against the associated switchable disc element 100 above the horizontal axis of rotation defined by its pivots 102. This causes the associated disc 100 to flip, forming an element of an alphanumeric character at the associated vertical position in a particular seven-high column of horizontally moving elements. On the other hand, when the control logic permits a particular control conduit 512 to issue a control jet pulse at the time that a power jet pulse issues from the associated power jet conduit 510, that power jet is made turbulent and expands to fill the associated chamber 516, thus distributing its impact spatially in a way that prevents flipping of the associated disc element 100. If desired, the expansion chambers 516 illustrated in FIG. could be preferentially enlarged in the downward direction for further enhancement of this eifect.

The moving display writing station illustrated in FIG. 5 thus provides a fluidic writing apparatus in which valves are not required to control the power jets directly. The resulting mechanism is cheaper and less troublesome both to manufacture and to maintain; it has a high immunity to sonic disturbances; it consumes relatively little fluid power; it occupies a minimal horizontal depth, and it makes sharp distinctions between the conditions for switching a disc element and the conditions for inhibiting such switching.

Since the foregoing description and drawings are merely illustrative, the scope of protection of the invention has been more broadly stated in the following claims; and these should be liberally interpreted so as to obtain the benefit of all equivalents to which the invention is fairly entitled.

I claim:

1. A non-translating fluid operated display unit comprising:

a switchable element;

means mounting said element for switching movement between two operating positions;

a first flow means adapted to direct a power jet of fluid at said element in such a manner that said element may be switched from one of said operating positions to the other in response to said jet;

a second flow means for directing a second power jet of fluid in such a manner that said element may be switched from said other position to said one position in response to said second jet;

and control means for selectively initiating and terminating said first and second power jets respectively.

2. Apparatus as defined in claim 1 wherein said control means includes a means for directing a control jet of fluid at at least one of said power jets.

3. Apparatus as defined by claim ll wherein said first power jet is in a laminar state when eflecting the said switching of said element.

4. Apparatus as defined by claim 3 wherein said control means causes said first power jet to be switched to its turbulent state.

5. Apparatus as defined by claim 4, additionally comprising an expansion chamber having walls surrounding said first power jet to promote lateral dispersion of said turbulent jet.

6. Apparatus as defined by claim 5 wherein said flow means is arranged to make said laminar power jet impinge on said element substantially exclusively on one side of an axis of rotation whereby to exert a net switching torque in a first angular direction upon said element.

7. Apparatus as defined by claim 6, additionally comprising an expansion chamber having walls surrounding said power jet, said chamber being arranged relative to the longitudinal axis of said power jet whereby to produce expansion of said turbulent jet so as to cause a greater portion of said turbulent jet to impinge on said element on the opposite side of said axis of rotation whereby at least to reduce said net torque in said first angular direction.

8. Fluid operated switching apparatus comprising:

a switchable element;

means mounting said element for rotative switching movement between two operating positions;

flow means adapted to direct a laminar power jet of -fluid toward said element in such a manner that said element is switched from one of said operating positions to the other in response to said laminar jet, said flow means being arranged to make said laminar jet impinge on said element substantially exclusively on one side of the axis of rotation thereof whereby to exert a net switching torque in a first angular direction upon said element;

control means for initiating and terminating said lamimar power jet, said control means being operable to control the switching of said power jet between laminar and turbulent flow states; and

an expansion chamber having walls surrounding said power jet, said chamber being arranged relative to the longitudinal axis of said power jet whereby to produce expansion of said turbulent jet so as to cause a greater portion of said turbulent jet to impinge on said element on the opposite side of said axis of rotation whereby at least to reduce said net torque in said first angular direction.

9. Apparatus as defined by claim 8 wherein said control means includes a means for directing a control jet of fluid at said laminar power jet.

10. Apparatus as defined by claim 8 wherein said element has substantially a sheet-like configuration; and wherein said mounting means includes a pivot arranged to allow said element rotatable about an axis substantially parallel to said sheet.

11. Apparatus as defined by claim 8 wherein said flow means is arranged to make said laminar power jet impinge on said element substantially exclusively on one side of said axis of rotation whereby to exert a net switching' torque in a first angular direction upon said element.

.12. Apparatus as defined by claim 8 for use in a moving character display comprising:

a plurality of said elements arranged in vertical columns, one of said mounting means for each of said elements;

a plurality of said flow means stacked one column high at stationary character writing location and arranged to be simultaneously operable; and

one of said control means for each of said flow means,

said control means being operable in selected combinations for controlling the switching of selected ones of a vertical column of said elements by said flow means.

13. Fluid operated switching apparatus comprising:

a switchable element;

means mounting said element for rotative switching movement between two operating positions;

flow means adapted to direct a. laminar power jet of fluid toward said element in such a manner that said element is switched from one of said operating positions to the other in response to said laminar jet, said flow means being arranged to make said laminar jet impinge on said element substantially exclusively on one side of the axis of rotation thereof whereby to exert a net switching torque in a first angular direction upon said element;

control means for initiating and terminating said laminar power jet, said control means being operable to control the switching of said power jet between laminar and turbulent flow states;

a second flow means arranged to direct a second laminar jet against said element substantially exclusive on the opposite side of said axis of rotation whereby to exert a net torque thereon in the opposite angular direction for resetting said element; and

second control means for making said second power jet turbulent.

14. Fluidic switching apparatus comprising:

a switchable element;

means mounting said element for rotative switching movement between two operating positions;

flow means adapted to direct a power jet of fluid at said element in such a manner that said element is switched from one of said operating positions to the other in response to said jet being in a laminar state, said jet exerting insufficient net force on said element for said switching thereof when said jet is in a turbulent state, said flow means being arranged to make said laminar power jet impinge on said element substantially exclusively on one side of said axis of rotation whereby to exert a net switching torque in a first angular direction upon said element;

control means for switching said power jet between said laminar and turbulent states, said control means including a means for directing a control jet of fluid at said power jet to make said power jet tubulent; and

an expansion chamber having walls surrounding said power jet, said chamber being arranged relative to the longitudinal axis of said power jet whereby to produce expansion of said turbulent jet so as to cause a greater portion of said turbulent jet to impinge on said element on the opposite side of said axis of rotation whereby at least to reduce said net torque in said first angular direction.

15. Apparatus as defined by claim 14 wherein said element has substantially a sheet-like configuration; and wherein said mounting means includes a pivot arranged to make said element rotatable about an axis substantially parallel to said sheet.

16. Apparatus as defined by claim 14, additionally comprising stop means for limiting rotation of said element about said axis of rotation whereby to define at least one of operating positions.

17. Apparatus as defined by claim 14, additionally comprising an expansion chamber having walls surrounding said power jet at the place where it emerges from said power conduit whereby to promote lateral dispersion of said turbulent jet.

18. Apparatus as defined by claim 14 for use in a moving character display comprising:

a plurality of said elements arranged in vertical columns, one of said mounting means for each of said elements;

a plurality of said flow means stacked one column high at a stationary character writing location and arranged to be simultaneously operable; and

one of said control means for each of said flow means,

said control means being operable in selected combinations for controlling the'switching of selected ones of a vertical column of said elements by said flow means.

19. Fluidic switching apparatus comprising:

a switchable element;

means mounting said element for rotative switching movement between two operating positions;

flow means adapted to direct a power jet of fluid at said element in such a manner that said element is switched from one of said operating positions to the other in response to said jet being in a laminar state, said jet exerting insuflicient net force on said element for said switching thereof when said jet is in a turbulent state, said flow means being arranged to make said laminar power jet impinge on said element substantially exclusively on one side of said axis of rotation whereby to exert a net switching torque in a first angular direction upon said element;

control means for switching said power jet between said laminar and turbulent states, said control means including a means for directing a control jet of fluid at said power jet to make said power jet turbulent;

a second flow means arranged to direct a second laminar jet against said element substantially exclusively on the opposite side of said axis of rotation whereby to exert a net torque thereon in the opposite angular direction for resetting said element; and

a second control means for making said second power jet turbulent.

20. A fluid operated display device comprising:

a display element having contrasting colors on different sides thereof;

mounting means for swingably supporting said display element for movement between display and nondisplay positions;

a first fluid jet means adapted to direct a jet of fluid towards said display element, said jet having two possible flow modes including a laminar fiow mode wherein said jet of fluid is laminar and is directed to a localized area of said display element so that said display element may thereby be swung from one of said positions to the other of said two positions, and a turbulent mode wherein said jet of fluid is turbulent and is incapable of swingably displacing said display element; and

a second fluid jet means adapted to direct a control jet of fluid against said first mentioned jet of fluid as to control the flow mode of the latter and thereby control displacement of said display element from said one to the other of said positions thereof.

21. Apparatus as defined by claim 20 wherein said one position is the non-display position of said element.

22. Apparatus as defined by claim 20, additionally comprising:

a third jet means for restoring said element to said one position; and

a fourth jet means for controlling said third jet means.

References Cited UNITED STATES PATENTS 1,205,530 11/1916 Hall 137-815 X 3,374,565 3/1968 Woolfolk 40-28 CX 3,395,471 8/1968 Rydstrom 40-28 3,429,323 2/1969 Mott 137-815 3,482,344 12/1969 Holloman 40-28 C 3,502,092 3/1970 Metzger 137-815 ROBERT W. MICHELL, Primary Examiner W. J. CONTRERAS, Assistant Examiner US. Cl. X.R. 40-37, 67 

